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Feed screw arrangement

a screw and screw head technology, applied in the direction of presses, manufacturing tools, grain treatment, etc., can solve the problems of difficult control of the direction of the chips, and the path of the chips is completely unpredictable, so as to improve the feeding of lignocellulose materials and reduce the risk of being rejected from the grinding zone

Inactive Publication Date: 2016-12-27
VALMET AB
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The solution provides a more predictable and efficient feeding of lignocellulose materials into the grinding zone, reducing the likelihood of material rejection and improving processing efficiency.

Problems solved by technology

In reality, it has been proven difficult to control the direction of the chips, which are just as often thrown back into the feed screw as they are thrown in the radial direction towards the grinding zone.
Normally, the path of a chip is completely unpredictable and often it bounces back and forth several times before it reaches the grinding zone.

Method used

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first embodiment

[0034]In the first embodiment shown in FIGS. 1 and 2 the angled end part 22 consists of a straight plate that is fixed to the peripheral thread 23 at an abrupt angle with respect to the feed screw. In this context an abrupt angle indicates that the angle of the end part 22 with respect to the peripheral thread 23 is achieved in one single point, such that pitch angle of the peripheral thread 23 gets a sudden increase by means of the angled end part 22. The pitch angle thus has one value upstream of the point of the abrupt angle and another, higher value, downstream of the same point. Due to the abrupt angle the chips will bounce on the angled end part 22 towards the peripheral grinding zone.

second embodiment

[0035]the angled end part 22 is shown in FIG. 3. In this embodiment the end part 22 has a smoothly curved surface arranged to provide a smooth transition for the chips, such that the chips will be swung towards the grinding zone. In this embodiment the increase of the pitch angle with respect to the peripheral thread 23 is smoothly increasing, instead of having an abrupt angle. An advantage of this embodiment is that the release angle of the chips will be easier to control, due to the fact that a more predictable trajectory of the chips may be achieved.

[0036]Both embodiments of the inventive angled end part may be easily implemented in an existing feeding arrangement, e.g., by welding a plate to the peripheral thread or by attaching it by means of an angle bar 26 on the peripheral thread 23. The peripheral thread 23 has a feeding side 27 which is in contact with the chips as they are fed through the cylindrical pipe 19. Naturally, the angled end part 22 is attached to this feeding s...

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Abstract

A feed screw for feeding lignocellulosic material to a rotary disc refiner is disclosed. The feed screw includes at least one peripheral thread for feeding the lignocellulosic material axially towards the disc refiner and the feed screw feeds the lignocellulosic material from its upstream end towards its downstream end through the center of the opposed grinding surfaces of the disc refiner, the downstream end of the peripheral thread including an angled end part disposed at an angle with respect to the peripheral thread such that the lignocellulosic material is redirected in a radial direction as it leaves the end of the peripheral thread.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application is a national phase entry under 35 U.S.C. §371 of International Application No. PCT / SE2012 / 000099 filed Jun. 28, 2012, published in English, which claims priority from SE 1150621-9, filed Jul. 1, 2011, all of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to a feed screw for feeding lignocellulose material to a rotary grinder. Specifically, the present invention relates to a feed screw arrangement for feeding lignocellulose material to a grinding zone of a rotary grinder.BACKGROUND OF THE INVENTION[0003]A rotary grinder may be used for grinding lignocellulose material, such as wood chips, into pulp. Such a grinder comprises two opposed grinding discs, which both include a peripheral ring-formed grinding surface between which the chips are to be ground. Normally, one of these discs is stationary, i.e., the stator disc, and the other is rotary, i.e., the rotor dis...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): B02C7/11D21D1/30D21B1/22
CPCD21B1/22B02C7/11D21D1/30B02C7/16B30B9/121B30B9/122
Inventor AHLGREN, ORJAN
Owner VALMET AB